custom logging under pm2

Question

I have some useful logging in my node app that I write to console.log

node server.js >> /var/log/nodeserver.log 2>&1

Answer 1

In case of new start, you just:

• run pm2 start/reload ecosystem.config.js [--only your_app]

But when it is already started (pm2 already managing it) you have to do (someone can find a better way, but this works for me):

• run pm2 delete your_app
• run pm2 start

Answer 2

One nifty feature is to use the logs feature in terminal:

pm2 logs [--raw]

this will live stream the all the logs. Other handy commands are:

• pm2 flush
• pm2 reloadLogs

Answer 3

When running with pm2 your application logs will reside in $HOME/.pm2/logs as described here. Verifying this locally with a simple index.js file that outputs console.log('test')

$ pm2 start index.js
[PM2] Spawning PM2 daemon
[PM2] PM2 Successfully daemonized
[PM2] Starting index.js in fork_mode (1 instance)
[PM2] Done.
┌──────────┬────┬──────┬───────┬────────┬─────────┬────────┬────────────┬──────────┐
│ App name │ id │ mode │ pid   │ status │ restart │ uptime │ memory     │ watching │
├──────────┼────┼──────┼───────┼────────┼─────────┼────────┼────────────┼──────────┤
│ index    │ 0  │ fork │ 36976 │ online │ 0       │ 0s     │ 9.258 MB   │ disabled │
└──────────┴────┴──────┴───────┴────────┴─────────┴────────┴────────────┴──────────┘
 Use `pm2 show <id|name>` to get more details about an app

Notice how I see no console.log output here, but, if I navigate to $HOME/.pm2/logs I see

logs $ ls
index-error-0.log   index-out-0.log

logs $ cat index-out-0.log
test

Answer 4

Update in 2017.

Define log path as parameter when pm2 command is executed (-l, -o, -e) is very easy to use and normally is the best choice.

However, if you don't want to define log path every time when pm2 is executed, you can generate a configuration file, define error_file and out_file, and start pm2 from that:

1. Generate a configuration file: pm2 ecosystem simple. This would generate a file ecosystem.config.js, with following content:

   module.exports = {
     apps : [{
       name   : "app1",
       script : "./app.js"
     }]
   }
   

2. Define error_file (for error log) and out_file (for info log) in the file, such as:

   module.exports = {
     apps : [{
       name   : "app1",
       script : "./app.js",
       error_file : "./err.log",
       out_file : "./out.log"
     }]
   }
   

3. Start the process from the configuration file:

   pm2 start ecosystem.config.js
   

In this way, the logs are saved to ./err.log and ./out.log.

Please refer to the document for detail information.